A wireless local area network (WLAN) is a very convenient data transmission system. By utilizing a radio frequency (RF) technology to take the place of a local area network formed by an old-fashioned troublesome twisted pair copper wire, the wireless local area network can achieve, by using a simple access architecture, an ideal state where information is readily accessible to people traveling around the world.
At present, in addition to data communication using the WLAN, a WLAN-based positioning function is also developed, where positioning can be implemented by using the WLAN.
In the prior art, an apparatus for reminding a user of an article left behind includes a transmitter disposed on an article, a receiver, and a triggering switch disposed on a door, and a reminder, where an on or off state of the triggering switch is controlled by opening or closing of the door. The reminder is electrically connected to both the receiver and the triggering switch, and a working state of the reminder is controlled by an output state of the receiver and an on or off state of the triggering switch. When a user leaves with the article, the receiver receives a signal from the transmitter, and the reminder does not work. When the user leaves without the article, the receiver does not receive a signal from the transmitter, and the triggering switch triggers the reminder to send a reminding signal.
The foregoing apparatus in the prior art for reminding a user of an article left behind has the following disadvantages. A receiver needs to be installed on a door, and a user needs to carry a transmitter, which is troublesome for the user and is relatively costly.